Arterial ischemic stroke in children

The Use of Contrast-Enhanced Ultrasound (CEUS) in the Evaluation of the Neonatal Brain

In recent years, advancements in technology have allowed the use of contrast-enhanced ultrasounds (CEUS) with high-frequency transducers, which in turn, led to new possibilities in diagnosing a variety of diseases and conditions in the field of radiology, including neonatal brain imaging. CEUSs overcome some of the limitations of conventional ultrasounds (US) and Doppler USs. It allows the visualization of dynamic perfusion even in the smallest vessels in the whole brain and allows the quantitative analysis of perfusion parameters. An increasing number of articles are published on the topic of the use of CEUSs on children each year. In the area of brain imaging, the CEUS has already proven to be useful in cases with clinical indications, such as hypoxic-ischemic injuries, stroke, intracranial hemorrhages, vascular anomalies, brain tumors, and infections. We present and discuss the basic principles of the CEUS and its safety considerations, the examination protocol for imaging the neonatal brain, and current and emerging clinical applications.

Intracranial Abnormalities with Diffusion Restriction

Multiple pathologic conditions can cause changes in the random movement of water, which can be detected with diffusion-weighted imaging (DWI). DWI plays a powerful clinical role in detecting restricted diffusion associated with acute brain infarction. Other disorders can also result in restricted diffusion. This article focuses on showing examples of common and uncommon disorders that have restricted diffusion secondary to cytotoxic and/or intramyelinic edema. These disorders include ischemia, infection, noninfectious demyelinating diseases, genetic mutations affecting metabolism, acquired metabolic disorders, toxic or drug exposures, neoplasms and tumorlike lesions, radiation treatment, trauma, and denervation.

A child with atypically subtle clinical presentation of acute arterial ischaemic stroke in the middle cerebral artery

Arterial ischaemic stroke in the paediatric population is considered a rare disease, and its diagnosis is often delayed due to the subtlety and variability of clinical symptoms, especially in younger patients. The clinical presentation and imaging features of ischaemic stroke in the paediatric population are variable depending on the underlying cause, affected artery and patient’s age. Literally, acute occlusion of the middle cerebral artery shows significant clinical signs and symptoms, and riotous imaging findings due to the size of the territory. Here, we present a case of a 15-year-old boy who unusually had subtle and intermittent clinical symptoms in spite of a complete acute occlusion in his right middle cerebral artery.

Epidemiology, Clinical Presentation, and Prognosis of Posterior Circulation Ischemic Stroke in Children

BACKGROUND

Anterior and posterior circulation strokes are often different in terms of presentation and recurrence risk, but there are few studies that focused on posterior circulation stroke.

METHODS

We performed a longitudinal retrospective study of children, birth to 18 years, with posterior circulation ischemic stroke at the Children's Hospital Winnipeg from January 1992 to December 2012. Clinical and radiological features and outcomes were collected using standardized tools.

RESULTS

Of the 158 children with arterial ischemic stroke, 23 (14.5%) children, 21 non-neonates, and 11 males were identified. For posterior circulation ischemic stroke, mean crude incidence of 0.38 and crude mortality rate of 0.11 per 100,000 person-years was estimated. The crude total period prevalence rate for the study period was estimated as 8.1 per 100,000 children. Nonspecific symptoms before stroke presentation were present in 38% and impaired consciousness in 71%. Identifiable risk factors were present in two thirds: vasculopathy 24%, infection 19%, trauma 14%, and congenital heart disease 9.5%. Average Pediatric National Institutes of Health Stroke Scale score at presentation was 11. Poor outcome was noted in 45%. Outcome did not change significantly between 12 and 24 months. Aboriginal ethnicity (P = 0.01), high Pediatric National Institutes of Health Stroke Scale score (P = 0.001), bilateral infarction (P = 0.001), and large caliber artery territory infarction (P = 0.02) predicted poor outcome.

CONCLUSIONS

Our hospital-based incidence and outcome data provide valuable information to help direct treatment strategies and prognosticate children with posterior circulation ischemic stroke. Our study calls for close observation and early management of children with posterior circulation stroke, in particular with aboriginal ancestry and bilateral and large artery territory infarction.

The role of imaging studies for evaluation of stroke in children

Stroke is a major cause of morbidity and mortality in children and long-term neurological deficits. Although cerebrovascular disorders occur less often in children than in adults, recognition of stroke in children has probably increased because of the widespread application of noninvasive diagnostic studies such as magnetic resonance imaging and computed tomography.Computed tomography (CT) should be the first imaging choice in the emergency setting when stroke is suspected. It will show the presence of hemorrhage (eg, bleeding from arteriovenous malformation). It is often normal within the first hours in arterial ischemic stroke. As in adults, magnetic resonance imaging is the neuroimaging modality to confirm the clinical diagnosis of ischemic stroke. In children, however, magnetic resonance imaging requires sedation and may not be as readily available as CT. Perfusion imaging demonstrates flow within the brain and can detect areas that are at risk of ischemia; however, further studies in the pediatric population need to be validated for this technique in children. Angiography detects arterial disease (eg, aneurysm); however, its use has been largely superseded by better magnetic resonance angiography, which is sensitive enough to visualize lesions in the proximal anterior cerebral artery, middle cerebral artery, and distal internal carotid artery (ICA). Magnetic resonance imaging using diffusion- weighted imaging is the most versatile and sensitive imaging technique for identifying ischemic lesions. In the future, we need to identify the pediatric patient presenting to the emergency department with an acute stroke and develop a pathway for the use of particular imaging techniques (eg, CT vs magnetic resonance imaging).

Stroke in Young People: The Increasing Role of Advanced Imaging

Ischemic stroke in young people is an unexpected event due to a wider variety of causes compared to the older population. This study highlights the increasing role of neuroimaging in the diagnosis, prognosis and treatment of young stroke patients. Thirty young adult patients (age range, 15–45 years) with acute ischemic stroke diagnosis were retrospectively included and studied at our institution during 2009. The mean age of patients was 35 years and 50% were men. The stroke etiology was established in 86% of cases (n=26), 7% (n=2) were due to atherosclerosis of the main vessels, 10% (n=3) were related to cardioembolism, 27% (n=8) were due to arterial dissection and 43% (n=13) responded to miscellaneous etiologies. The cause remained unexplained in 14% (n=4) of cases. The aims of neuroimaging in the challenging study of young stroke patients are to confirm the ischemic nature of the lesion, to determine its location, and to verify the patency of major neck and intracranial arteries. Both MRI and MSCT offer the best sensitivity and spatial resolution.

Non-invasive imaging of intracranial pediatric vascular lesions

OBJECTIVES

The goal of this review is to discuss the different non-invasive imaging techniques as well as the age-specific pediatric vascular pathologies and their imaging features.

MATERIAL AND METHODS

Ultrasound, computed tomography, and magnetic resonance imaging features of pediatric ischemic stroke, intracranial hemorrhage, aneurysms, cavernomas, developmental venous anomalies, and arteriovenous malformations are presented. In addition, multiple non-invasive angiographic techniques (CT and MR angiography) and functional MRI sequences (diffusion, perfusion, and susceptibility-weighted imaging) are discussed.

CONCLUSION

Neurovascular imaging plays a central role in the early, sensitive, and specific diagnosis of pediatric intracranial vascular disorders. A detailed knowledge of the quality and exact angioarchitecture of pediatric vascular pathologies as well as their impact on the cerebral hemo-dynamics is essential to guide and monitor treatment options and to predict functional outcome.